Gastro-oesophageal reflux monitoring: review and consensus report on detection and definitions of acid, non-acid, and gas reflux

Abstract

To date, most concepts on the frequency of gastro-oesophageal reflux episodes and the efficiency of the antireflux barrier have been based on inferences derived from measurement of oesophageal pH. The development of intraluminal impedance monitoring has highlighted the fact that pH monitoring does not detect all gastro-oesophageal reflux events when little or no acid is present in the refluxate, even if special pH tracing analysis criteria are used. In November 2002, a workshop took place at which 11 specialists in the field of gastro-oesophageal reflux disease discussed and criticised all currently available techniques for measurement of reflux. Here, a summary of their conclusions and recommendations of how to achieve the best results from the various techniques now available for reflux measurement is presented.

Figure 1

Effect of pH sampling rate on determination of oesophageal acid exposure and number of gastro-oesophageal reflux episodes.

Figure 2

Example of gastro-oesophageal reflux detected by a pH manometric recording. Acid reflux (pH drop to below 4) occurs during a transient lower oesophageal sphincter relaxation (tLOSR). A common cavity phenomenon can be observed in the manometric tracing as an abrupt increase in oesophageal body pressure to intragastric pressure levels.

Figure 3

Oesophageal intraluminal impedance monitoring combined with oesophageal and gastric pH measurements. Gastro-oesophageal reflux is detected as an orally progressing drop in impedance, starting at the level of the lower oesophageal sphincter and propagating to more proximal impedance measuring segments. In this tracing, three reflux episodes can be observed: (A) acid reflux (mixed liquid-gas); (B) and (C), superimposed reflux episodes (liquid).

Figure 4

Tracings during a slow pull through of a combined manometric impedance catheter across the gastro-oesophageal junction. Patients with gastro-oesophageal reflux disease (GORD) have lower basal impedance values in the distal oesophageal body compared with healthy subjects. LOS, lower oesophageal sphincter.

Figure 5

In neonates, the high frequency of feeds results in a significant number of reflux episodes (detected as common cavities (CC)) not causing a drop in oesophageal pH across 4. GOR, gastro-oesophageal reflux.

Figure 6

Definitions of reflux are based on the pH of the refluxate. Acid reflux (A) is defined as reflux that reduces oesophageal pH to below 4 or reflux that occurs when oesophageal pH is already below 4. Superimposed acid reflux is a subcategory of acid reflux. Weakly acidic reflux (B) is defined as a pH fall of at least 1 unit where the pH does not fall below 4, and a pH of 7 is the cut off between “weakly acidic” and “non-acid reflux”. Weakly alkaline reflux (C) is defined as a reflux episode during which nadir oesophageal pH does not drop below 7.

Figure 7

In infants, basal oesophageal pH is often between 5 and 6 and a reflux event detected by impedance might not change the oesophageal pH.

Figure 8

Simultaneous pH impedance-Bilitec recordings: oesophageal bilirubin concentration monitoring adds information about the chemical nature of acid and non-acid material that refluxes into the oesophagus. Weakly acidic and weakly alkaline reflux may or may not include duodenal contents